Fixture for turning inner hole of thin-wall step-shaped cylindrical part

Abstract

The invention discloses a clamp for turning an inner hole of a thin-wall step-shaped cylindrical part. The clamp aims at solving the problems that in the machining process of the thin-wall step-shaped cylindrical part, the positioning precision is insufficient, and deformation is caused by uneven clamping force. The clamp comprises a clamp positioning sleeve, a connecting disc, a spring expansion sleeve, a taper sleeve, a positioning disc and a driving device, and a workpiece is rapidly clamped and loosened through axial movement of the spring expansion sleeve. The clamping teeth at the free end of the spring expansion sleeve and the taper sleeve hold the large-diameter section and the small-diameter section of the thin-wall step-shaped cylindrical part respectively, clamping force is evenly distributed in the circumferential direction of a workpiece, and workpiece deformation caused by uneven or too large clamping force is effectively avoided. The combination of the taper sleeve and the spring expansion sleeve ensures the coaxiality of the workpiece and the main shaft of the numerical control lathe, and improves the positioning accuracy. The driving device adopts a numerical control lathe spindle cylinder, the automation degree is high, and the machining efficiency is greatly improved. The device is compact in structure, accurate in positioning, convenient to operate and suitable for high-precision machining of thin-wall stepped cylindrical parts.

Description

Technical Field

[0001] The invention relates to the field of turning fixtures, in particular to a fixture for turning the inner hole of a thin-walled stepped cylindrical part. Background Art

[0002] When turning the inner hole of a thin-walled stepped cylindrical part, the inner hole is required to have a high degree of concentricity with the outer circle of the thin-walled stepped cylindrical part. At the same time, the wall thickness is thin, and the thin-walled stepped cylindrical part has high requirements for clamping positioning accuracy and clamping force control during processing. If the hydraulic three-jaw chuck commonly equipped on the lathe is directly used to clamp the workpiece, on the one hand, the positioning accuracy of the three-jaw chuck is difficult to meet the processing requirements, and on the other hand, the clamping force of the hydraulic three-jaw chuck on the thin-walled part is uneven, which can easily cause deformation of the thin-walled stepped cylindrical part.

[0003] CN104493600A The invention discloses "special tooling for turning the inner hole of a high-precision thin-walled cylinder sleeve, including an inner fixing sleeve, an elastic clamp, and an axial positioning disk. The left end of the inner fixing sleeve is connected to the spindle receiving disk, and the right end of the inner fixing sleeve is connected to the axial positioning disk. A tapered hole is provided on the right side of the inner fixing sleeve, and the tapered hole is connected to the cylindrical hole on the left side. A guide hole is provided on the side wall of one side of the cylindrical hole, and an air outlet is provided on the left side of the guide hole. The elastic clamp includes an inner cylindrical hole and an outer conical surface, and the outer conical surface is connected to the outer cylindrical surface. A tie rod fixing seat is provided on the outer cylindrical surface, and a tie rod fixing seat is provided with a tie rod fixing hole. A gasket is provided on the right side of the tie rod fixing hole, and the outer diameter of the gasket is larger than the inner diameter of the tie rod fixing hole. The outer circle of the end of the cylinder tie rod cooperates with the tie rod fixing hole, and a threaded hole is provided at the end of the cylinder tie rod, and the cylinder tie rod is connected to the gasket. The present invention has high structural precision, reliable positioning and clamping of the thin-walled cylinder sleeve, uniform clamping force, reduced deformation of the thin-walled cylinder sleeve due to the clamping force, and meets the precision requirements of the workpiece". Although the tooling supports the thin-walled cylinder liner circumferentially through the elastic sleeve, the thin-walled cylinder liner is subjected to uniform force, thereby effectively reducing the deformation caused by uneven clamping force, thereby improving the processing accuracy.

[0004] However, this special tool is only suitable for turning the inner hole of thin-walled cylinder sleeves, and cannot hold and fix thin-walled stepped cylindrical parts. If this special tool is used forcibly to hold, the large diameter section of the thin-walled stepped cylindrical parts will be subjected to excessive holding force, resulting in deformation, and the requirements for processing accuracy cannot be met. Therefore, the existing technology cannot effectively solve the problem of precise positioning and preventing deformation during the clamping process of thin-walled stepped cylindrical parts. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the present invention provides a fixture for turning the inner hole of a thin-walled stepped cylindrical part. The fixture realizes efficient clamping and loosening of the workpiece through the axial movement of the spring expansion sleeve, and can hold the workpiece to be processed circumferentially, with uniform clamping force, reducing the deformation of the thin-walled stepped cylindrical part caused by the clamping force, and the spring expansion sleeve and the inner hole of the cone sleeve can respectively hold the large diameter section and the small diameter section of the thin-walled stepped cylindrical part, thereby improving positioning accuracy and production efficiency.

[0006] The technical solution of the present invention is achieved in this way: A fixture for turning the inner hole of a thin-walled stepped cylindrical part comprises a fixture positioning sleeve and a connecting plate. The fixture positioning sleeve and the connecting plate are fixed by bolts. The connecting plate is used to connect with the spindle flange of a CNC lathe. A spring expansion sleeve is fitted in the clearance inside the center hole of the fixture positioning sleeve. The fixed end of the spring expansion sleeve is provided with an internal thread which is threadedly connected with an external thread of a connecting sleeve. The connecting sleeve is provided with an internal thread for connecting a driving device. The fixed end of the spring expansion sleeve is provided with a plurality of axially extending openings on its circumference. A positioning plate is provided in the spring expansion sleeve hole. The circumference of the positioning plate is provided with a plurality of convex Teeth, the convex teeth pass through the opening of the spring expansion sleeve and are threadedly connected to the inner wall of the fixture positioning sleeve, the free end of the spring expansion sleeve is provided with clamping teeth extending toward the center of the circle, a tapered sleeve is gap-matched in the supporting tapered hole in the middle of the spring expansion sleeve, one end of the inner hole of the tapered sleeve is gap-matched with the shaft section of the positioning plate, a spring is arranged between the positioning plate and the tapered sleeve, a guide tapered hole is arranged at the mouth end of the fixture positioning sleeve, and an inverted tapered section opposite to the guide tapered hole is arranged on the outer circle of the free end of the spring expansion sleeve, and the spring expansion sleeve moves axially along the inner hole of the fixture positioning sleeve, so that the free end of the spring expansion sleeve clamps or releases the workpiece.

[0007] Preferably, the driving device is a cylinder provided on the spindle of the CNC lathe, the external thread provided on the cylinder is threadedly connected with the internal thread provided on the connecting sleeve, and the cylinder provides power for the axial movement of the spring expansion sleeve along the inner hole of the fixture positioning sleeve.

[0008] Preferably, a washer is arranged between the spring and the cone sleeve, and the spring and the washer are both sleeved on the shaft section of the positioning plate.

[0009] Preferably, the spring is a disc spring in a pair combination.

[0010] Preferably, a positioning hole is opened on the side wall of the supporting conical hole in the middle part of the spring expansion sleeve, and a positioning screw is arranged in the positioning hole. The lower end of the positioning screw cooperates with the axially extending strip groove provided on the circumferential outer wall of the cone sleeve to fix the cone sleeve circumferentially in the supporting conical hole in the middle part of the spring expansion sleeve.

[0011] Preferably, a plurality of gas outlet process holes are provided on the side wall of the fixture positioning sleeve.

[0012] Preferably, an external thread is provided on the outer periphery of the protruding teeth of the positioning plate to be threadedly connected with the inner wall thread of the fixture positioning sleeve.

[0013] Preferably, the coupling plate is fixedly connected to the spindle flange of the CNC lathe by bolts.

[0014] Preferably, the inner hole of the clamping tooth at the free end of the spring expansion sleeve is used to hold the large diameter section of the standard part, and the inner hole of the tapered sleeve is used to hold the small diameter section of the standard part. The inner hole diameter of the clamping tooth at the free end of the spring expansion sleeve is larger than the inner hole diameter of the tapered sleeve.

[0015] The beneficial effects of the present invention are as follows: The present invention uses the clamping tooth structure and the tapered sleeve at the free end of the spring expansion sleeve to respectively clamp the large diameter section and the small diameter section of the thin-walled stepped cylindrical part, and the clamping force is evenly distributed in the circumference of the workpiece, thereby effectively avoiding the problem of workpiece deformation caused by uneven or excessive clamping force; The spring expansion sleeve and the taper sleeve ensure the coaxiality between the thin-walled stepped cylindrical parts and the CNC lathe spindle flange during the clamping process, realize the precise positioning of the workpiece, and greatly improve the processing accuracy; The present invention adopts a cylinder as a driving device, and drives the spring expansion sleeve to move axially through the connecting sleeve, so as to realize rapid clamping and loosening of the workpiece, greatly improve the clamping efficiency, and have a high degree of automation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a structural schematic diagram of the coupling disc in the present invention; Figure 3 It is a structural schematic diagram of the fixture positioning sleeve in the present invention; Figure 4 It is a schematic diagram of the axial structure of the positioning disk in the present invention; Figure 5 It is a structural schematic diagram of the cone sleeve in the present invention; Figure 6 It is a structural schematic diagram of the spring expansion sleeve in the present invention; Figure 7 It is a structural schematic diagram of the connecting sleeve in the present invention; Figure 8 It is a schematic diagram of the structure of the standard parts in the present invention. DETAILED DESCRIPTION

[0017] See also Figures 1 to 8; A fixture for turning the inner hole of a thin-walled stepped cylindrical part, comprising a fixture positioning sleeve 3 and a connecting plate 1. The flange-shaped fixing plate arranged at the fixed end of the fixture positioning sleeve 3 is fixed to the connecting plate 1 by bolts. The connecting plate 1 is fixedly connected to the flange plate 2 of the CNC lathe spindle by bolts. A spring expansion sleeve 8 is fitted in the clearance in the center hole of the fixture positioning sleeve 3. The fixed end of the spring expansion sleeve 8 is provided with an internal thread which is threadedly connected to an external thread of a connecting sleeve 11. The connecting sleeve 11 is provided with an internal thread for connecting a driving device. The driving device is a cylinder provided on the CNC lathe spindle. The external thread provided on the cylinder is threadedly connected to the internal thread provided on the connecting sleeve 11. The cylinder is a spring expansion sleeve. The sleeve 8 provides power for axial movement along the inner hole of the fixture positioning sleeve 3. The fixed end circumference of the spring expansion sleeve 8 is provided with multiple axially extending openings 15. A positioning plate 4 is arranged in the hole of the spring expansion sleeve 8. The circumference of the positioning plate 4 is provided with multiple convex teeth 12. The convex teeth 12 pass through the openings 15 of the spring expansion sleeve 8. The outer circumference of the convex teeth 12 of the positioning plate 4 is provided with external threads that are threadedly connected with the inner wall threads of the fixture positioning sleeve 3. The free end of the spring expansion sleeve 8 is provided with clamping teeth extending toward the center of the circle. A tapered sleeve 10 is fitted with a clearance in the supporting tapered hole 16 in the middle of the spring expansion sleeve 8. One end of the inner hole of the tapered sleeve 10 is clearance-matched with the shaft section of the positioning plate 4. The positioning plate 4 and the tapered sleeve 10 are clearance-matched. A spring 5 is arranged between the spring 5 and the cone sleeve 10, and a washer 6 is arranged between the spring 5 and the cone sleeve 10. The washer 6 is used to make up for the insufficient axial length of the spring 5. The spring 5 and the washer 6 are both sleeved on the shaft section of the positioning disk 4. The spring 5 is a disc spring of a matching combination. The mouth end of the fixture positioning sleeve 3 is provided with a guide cone hole, and the outer circle of the free end of the spring expansion sleeve 8 is provided with an inverted cone section opposite to the guide cone hole. When the cylinder drives the spring expansion sleeve 8 to move axially along the inner hole of the fixture positioning sleeve 3, the guide cone hole arranged at the mouth end of the fixture positioning sleeve 3 cooperates with the inverted cone section of the spring expansion sleeve 8, so that the free end of the spring expansion sleeve 8 clamps or releases the workpiece, and the side wall of the supporting cone hole 16 in the middle of the spring expansion sleeve 8 is provided. A positioning hole is provided, in which a positioning screw 13 is arranged, and the lower end of the positioning screw 13 cooperates with the axially extending strip groove provided on the outer wall of the tapered sleeve 10 to fix the tapered sleeve 10 circumferentially in the supporting tapered hole 16 in the middle of the spring expansion sleeve 8. The spring 5 abuts the tapered sleeve 10 with the supporting tapered hole 16 and axially fixes the tapered sleeve 10 in the supporting tapered hole 16. A plurality of air outlet process holes 14 are provided on the side wall of the fixture positioning sleeve 3; the inner hole of the clamping tooth at the free end of the spring expansion sleeve 8 is used to hold the large diameter section of the standard part 9, and the inner hole of the tapered sleeve 10 is used to hold the small diameter section of the standard part 9. The inner hole diameter of the clamping tooth at the free end of the spring expansion sleeve 8 is larger than the inner hole diameter of the tapered sleeve 10.

[0018] When in use, first fix the fixture for turning the inner hole of the thin-walled stepped cylindrical part on the CNC lathe spindle flange 2, and connect the connecting sleeve 11 to the cylinder provided on the CNC lathe spindle, install the standard part 9 into the tooling fixture, and the cylinder drives the spring expansion sleeve 8 and the taper sleeve 10 to clamp the standard part 9. Use the micrometer set on the CNC lathe bed to check the radial runout of the standard part 9 to 0.003mm. After meeting the standard, loosen the standard part 9, install the part to be processed, and drive the spring expansion sleeve 8 and the taper sleeve 10 to clamp the part to be processed, and then turn the part to be processed, and repeat this cycle.

[0019] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A fixture for turning the inner hole of a thin-walled stepped cylindrical part, comprising a fixture positioning sleeve (3) and a connecting plate (1), characterized in that: The fixture positioning sleeve (3) is fixed to the connecting plate (1) by bolt connection. The connecting plate (1) is used to connect to the CNC lathe spindle flange (2). A spring expansion sleeve (8) is fitted in the clearance inside the center hole of the fixture positioning sleeve (3). The fixed end of the spring expansion sleeve (8) is provided with an internal thread which is threadedly connected to the external thread of a connecting sleeve (11). The connecting sleeve (11) is provided with an internal thread for connecting to a driving device. The fixed end of the spring expansion sleeve (8) is provided with a plurality of axially extending openings (15) on its circumference. A positioning plate (4) is provided in the hole of the spring expansion sleeve (8). The positioning plate (4) is provided with a plurality of convex teeth (12) on its circumference. The convex teeth (12) pass through the spring expansion sleeve (8). The opening (15) is threadedly connected to the inner wall of the fixture positioning sleeve (3); the free end of the spring expansion sleeve (8) is provided with clamping teeth extending toward the center of the circle; a tapered sleeve (10) is clearance-matched in the supporting tapered hole (16) in the middle of the spring expansion sleeve (8); one end of the inner hole of the tapered sleeve (10) is clearance-matched with the shaft section of the positioning disk (4); a spring (5) is arranged between the positioning disk (4) and the tapered sleeve (10); a guide tapered hole is arranged at the mouth end of the fixture positioning sleeve (3); an inverted tapered section is arranged on the outer circle of the free end of the spring expansion sleeve (8) opposite to the guide tapered hole; the spring expansion sleeve (8) moves axially along the inner hole of the fixture positioning sleeve (3) so that the free end of the spring expansion sleeve (8) clamps or releases the workpiece.

2. The fixture for turning the inner hole of a thin-walled stepped cylindrical part according to claim 1, characterized in that: The driving device is a cylinder provided on the spindle of the CNC lathe, wherein the external thread provided on the cylinder is threadably connected to the internal thread provided on the connecting sleeve (11), and the cylinder provides power for the axial movement of the spring expansion sleeve (8) along the inner hole of the fixture positioning sleeve (3).

3. The fixture for turning the inner hole of a thin-walled stepped cylindrical part according to claim 1, characterized in that: A washer (6) is arranged between the spring (5) and the cone sleeve (10), and the spring (5) and the washer (6) are both sleeved on the shaft section of the positioning plate (4).

4. The fixture for turning the inner hole of a thin-walled stepped cylindrical part as claimed in claim 3, characterized in that: The spring (5) is a disc spring that is combined into a pair.

5. The fixture for turning the inner hole of a thin-walled stepped cylindrical part according to claim 1, characterized in that: A positioning hole is provided on the side wall of the supporting conical hole (16) in the middle of the spring expansion sleeve (8), and a positioning screw (13) is arranged in the positioning hole. The lower end of the positioning screw (13) cooperates with an axially extending strip groove provided on the outer wall of the conical sleeve (10) to fix the conical sleeve (10) circumferentially in the supporting conical hole (16) in the middle of the spring expansion sleeve (8).

6. The fixture for turning the inner hole of a thin-walled stepped cylindrical part according to claim 1, characterized in that: A plurality of gas outlet process holes (14) are provided on the side wall of the fixture positioning sleeve (3).

7. The fixture for turning the inner hole of a thin-walled stepped cylindrical part according to claim 1, characterized in that: An external thread is arranged on the outer periphery of the protruding teeth (12) of the positioning plate (4) and is threadably connected to the inner wall thread of the fixture positioning sleeve (3).

8. The fixture for turning the inner hole of a thin-walled stepped cylindrical part according to claim 1, characterized in that: The connecting plate (1) is fixedly connected to the CNC lathe spindle flange (2) via bolts.

9. The fixture for turning the inner hole of a thin-walled stepped cylindrical part according to claim 1, characterized in that: The inner hole of the clamping teeth at the free end of the spring expansion sleeve (8) is used to hold the large diameter section of the standard part (9), and the inner hole of the tapered sleeve (10) is used to hold the small diameter section of the standard part (9). The inner hole diameter of the clamping teeth at the free end of the spring expansion sleeve (8) is larger than the inner hole diameter of the tapered sleeve (10).

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